1. Field of the Invention
The embodiments herein generally relate to dicing of wafers into chips and more particularly to a process that bonds free metals left on the exterior of the chips to corresponding chemistries to create molecules that are incapable of diffusing back into the interior of the chip, which prevents unwanted metal contamination of the interior of the chip.
2. Background of the Invention
Preliminary laser dicing is often used in the die singulation process (process of dividing a wafer into single, individual chips) to prevent large initial flaws (that can develop into cracks) at the edges of the chips. Typical dicing methods involve these initial laser cuts followed by final saw cuts. However, in sensitive or high stress chips, even laser dicing as described above may not suffice and may result in initial flaws that are beyond a critical size. If an initial flaw turns into a crack, it can propagate into the chip. Chip package interaction (CPI) stresses arising out of the thermal expansion mismatch between chip and package can result in catastrophic failures during thermal cycling. Typically, these may be manifest as delamination of layers within the chip at the back end of the processing line (BEOL). Further some chip dicing processes can leave metals on the exterior of the chips.